Samenvatting
Three developments for low pressure sodium lamps for energy conservation are discussed. Firstly a change in construction of the cap for isolating the heat is given. Secondly new developments of the durability of low pressure sodium lamps are mentioned. Thirdly the construction of low pressure sodium lamp of 18 Watt, possible by the heat isolation is given. A luminous efficacy of 100 Lm/W is obtained.